Semiconductor devices which include a group III-nitride compound, such as gallium nitride, are used in a device which operates at high frequencies or using high operating voltages. Group III-nitride compounds are also used in optoelectronic devices such as light emitting diodes (LEDs). In order to increase conductivity of the group III-nitride compounds, silicon or magnesium is implanted into source and drain regions of the group III-nitride compound and dopant activation using an annealing process. The implantation process and annealing process increase a number of charge carriers in the group III-nitride compound.